Leukocyte chemotactic cytokine and leukocyte subset responses during ultra-marathon running

The aim of this study was to assess leukocyte chemotactic cytokine and leukocyte subset responses during ultra-marathon running. Leukocyte chemokines such as interleukin (IL)-8, interferon gamma-induced protein-10 (IP-10), regulated upon activation, normal T-cell expressed and secreted (RANTES), and eotaxin are involved in leukocyte recruitment.

Among 60 male amateur endurance runner volunteers, 18 finished the course (a 308 km continuous race from Kanghwado to Kangneung, South Korea). Their average age, height, and body mass were 52.8 ± 5.0 years, 167.6 ± 5.2 cm, and 64.5 ± 1.2 kg, respectively. Blood samples were collected at 0, 100, 200, and 308 km during the race for analysis of white blood cells and serum concentrations of IL-8, IP-10, RANTES, eotaxin, IL-6, creatine kinase (CK), and C-reactive protein (CRP).

Muscle and liver damage indicators (IL-6, CK, and CRP) were maximally elevated as a result of marathon running. Total leukocytes, neutrophils, and monocytes increased significantly during the event (leukocytosis, neutrophilia, and monocytosis, respectively). However, lymphocytes and eosinophils decreased significantly during the event (lymphopenia and eosinopenia, respectively). Serum levels of the neutrophil chemokine IL-8 increased maximally at 100 km and were maintained. Monocyte-lymphocyte chemokine IP-10 concentration decreased during the latter part of the race. The eosinophil chemokine eotaxin decreased gradually during the race, and no difference was observed in eosinophil chemokine RANTES levels.

These observations indicate that prolonged endurance ultra-marathon running was associated with significant systemic inflammation and perturbation in leukocyte subsets. Leukocyte chemotactic cytokines such as IL-8, IP-10, eotaxin showed similar patterns of responses in related leukocyte subsets, but RANTES did not.